NAME

SYNOPSIS

ARGUMENTS

- display

connection to the X server

- window

event window, or None

- percent

relative volume, which can range from -100 to 100 inclusive

- name

a bell name, or NULL

DESCRIPTION

The core X protocol allows only applications to explicitly sound the system bell
with a
given duration, pitch, and volume. Xkb extends this capability by allowing
clients to
attach symbolic names to bells, disable audible bells, and receive an event
whenever the
keyboard bell is rung. For the purposes of this document, the
audible
bell is defined to be the system bell, or the default keyboard bell, as opposed
to any
other audible sound generated elsewhere in the system.
You can ask to receive XkbBellNotify events when any client rings any one of the
following:

*

The default bell

*

Any bell on an input device that can be specified by a bell_class and bell_id
pair

*

Any bell specified only by an arbitrary name. (This is, from the server's point
of view,
merely a name, and not connected with any physical sound-generating device. Some
client
application must generate the sound, or visual feedback, if any, that is
associated with
the name.)

You can also ask to receive XkbBellNotify events when the server rings the
default bell
or if any client has requested events only (without the bell sounding) for any
of the
bell types previously listed.

You can disable audible bells on a global basis. For example, a client that
replaces the
keyboard bell with some other audible cue might want to turn off the AudibleBell
control
to prevent the server from also generating a sound and avoid cacophony. If you
disable
audible bells and request to receive XkbBellNotify events, you can generate
feedback
different from the default bell.

You can, however, override the AudibleBell control by calling one of the
functions that
force the ringing of a bell in spite of the setting of the AudibleBell control -
XkbForceDeviceBell
or
XkbForceBell.
In this case the server does not generate a bell event.

Just as some keyboards can produce keyclicks to indicate when a key is pressed
or
repeating, Xkb can provide feedback for the controls by using special beep
codes. The
AccessXFeedback control is used to configure the specific types of operations
that
generate feedback.

Bell Names

You can associate a name to an act of ringing a bell by converting the name to
an Atom
and then using this name when you call the functions listed in this chapter. If
an event
is generated as a result, the name is then passed to all other clients
interested in
receiving XkbBellNotify events. Note that these are arbitrary names and that
there is no
binding to any sounds. Any sounds or other effects (such as visual bells on the
screen)
must be generated by a client application upon receipt of the bell event
containing the
name. There is no default name for the default keyboard bell. The server does
generate
some predefined bells for the AccessX controls. These named bells are shown in
Table 1 below; the name is included in any bell event sent to clients that have
requested to receive XkbBellNotify events.

Table 1 Predefined Bells

Action

Named Bell

Indicator turned on

AX_IndicatorOn

Indicator turned off

AX_IndicatorOff

More than one indicator changed state

AX_IndicatorChange

Control turned on

AX_FeatureOn

Control turned off

AX_FeatureOff

More than one control changed state

AX_FeatureChange

SlowKeys and BounceKeys about to be turned on or off

AX_SlowKeysWarning

SlowKeys key pressed

AX_SlowKeyPress

SlowKeys key accepted

AX_SlowKeyAccept

SlowKeys key rejected

AX_SlowKeyReject

Accepted SlowKeys key released

AX_SlowKeyRelease

BounceKeys key rejected

AX_BounceKeyReject

StickyKeys key latched

AX_StickyLatch

StickyKeys key locked

AX_StickyLock

StickyKeys key unlocked

AX_StickyUnlock

Audible Bells

Using Xkb you can generate bell events that do not necessarily ring the system
bell. This
is useful if you need to use an audio server instead of the system beep. For
example,
when an audio client starts, it could disable the audible bell (the system bell)
and then
listen for XkbBellNotify events. When it receives a XkbBellNotify event, the
audio client
could then send a request to an audio server to play a sound.

You can control the audible bells feature by passing the XkbAudibleBellMask to
XkbChangeEnabledControls.
If you set XkbAudibleBellMask on, the server rings the system bell when a bell
event
occurs. This is the default. If you set XkbAudibleBellMask off and a bell event
occurs,
the server does not ring the system bell unless you call
XkbForceDeviceBell
or
XkbForceBell.

Audible bells are also part of the per-client auto-reset controls.

Bell Functions

Use the functions described in this section to ring bells and to generate bell
events.

The input extension has two types of feedbacks that can generate bells - bell
feedback
and keyboard feedback. Some of the functions in this section have
bell_class
and
bell_id
parameters; set them as follows: Set
bell_class
to BellFeedbackClass or KbdFeedbackClass. A device can have more than one
feedback of
each type; set
bell_id
to the particular bell feedback of
bell_class
type.

Table 2 shows the conditions that cause a bell to sound or an XkbBellNotifyEvent
to be generated when a bell function is called.

Table 2 Bell Sounding and Bell Event Generating

Function called

AudibleBell

Server sounds a bell

Server sends an

XkbBellNotifyEvent

XkbDeviceBell

On

Yes

Yes

XkbDeviceBell

Off

No

Yes

XkbBell

On

Yes

Yes

XkbBell

Off

No

Yes

XkbDeviceBellEvent

On or Off

No

Yes

XkbBellEvent

On or Off

No

Yes

XkbDeviceForceBell

On or Off

Yes

No

XkbForceBell

On or Off

Yes

No

If a compatible keyboard extension isn't present in the X server,
XkbBell
calls
XBell
with the specified
display
and
percent,
and returns False. Otherwise,
XkbBell
calls
XkbDeviceBell
with the specified
display, window, percent,
and
name,
a
device_spec
of XkbUseCoreKbd, a
bell_class
of XkbDfltXIClass, and a
bell_id
of XkbDfltXIId, and returns True.
If you have disabled the audible bell, the server does not ring the system bell,
although it does generate a XkbBellNotify event.
You can call
XkbBell
without first initializing the keyboard extension.

RETURN VALUES

FALSE

The XkbBell function returns FALSE if XlibDisplayNoXkb is set.

STRUCTURES

Xkb generates XkbBellNotify events for all bells except for those resulting from
calls to
XkbForceDeviceBell
and
XkbForceBell.
To receive XkbBellNotify events under all possible conditions, pass
XkbBellNotifyMask in
both the
bits_to_change
and
values_for_bits
parameters to
XkbSelectEvents.

The XkbBellNotify event has no event details. It is either selected or it is
not.
However, you can call
XkbSelectEventDetails
using XkbBellNotify as the
event_type
and specifying XkbAllBellNotifyMask in
bits_to_change
and
values_for_bits.
This has the same effect as a call to
XkbSelectEvents.